Avalanche forecast

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Sawtooth Avalanche Center
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Avalanche danger

Sat
Alpine
4 · High
Treeline
3 · Considerable
Below
3 · Considerable
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Out of date — this forecast expired 4 years ago. You’re viewing past conditions, not the current bulletin.

Highlights

Very dangerous avalanche conditions exist. An exceptionally weak layer of snow lies beneath recent snowfall. You could trigger 2-3 foot thick avalanches on many steep slopes, including those in terrain relatively sheltered from the wind. Cracking and collapsing of the snowpack are clear indicators that the snowpack is unstable. Avalanches may be triggered remotely—from gentler terrain above, below, and to the sides of steep slopes.

Avalanche problems

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Very Likely
    Size
    2–3

    Expect to find 2-3' thick slabs atop exceptionally weak faceted snow and crusts. These slabs exist on all slopes and at all elevations. They will be thicker, stiffer, and capable of producing more destructive avalanches at middle and upper elevations that are exposed to the wind. 

    Yesterday, observers from across the forecast area reported several natural and human-triggered avalanches. Many of these were in atypical locations exemplifying the unusually touchy nature of the weak snow layer that lies beneath recent snowfall.

    Remotely triggering an avalanche is a real possibility. A collapse on gentle, or flat terrain in a valley bottom or ridgetop can quickly travel hundreds of feet to release an avalanche in steeper terrain. It's imperative that you pay close attention to the terrain that you're connected to or traveling beneath. This consideration is not only important for you and your group but for the safety of others.

Avalanche Discussion

The AVALANCHE WARNINGS have expired. The spike in natural avalanche activity has passed, but human-triggered avalanches remain very likely.

5-day storm totals reached 2-4' of snow (2.5-3.1" SWE) in this zone, with the vast majority of that falling since Wednesday. This thick slab of storm snow is perched on a 1 in 5 (1 in 10?) year weak layer. The sensitivity and widespread nature of this layer has impressed SAC Forecasters, local snow professionals, and longtime local observers alike. Numerous avalanches were reported in the Warm Springs Ck Drainage near Ketchum, one of which buried 50' of road with 8' of debris. Several small avalanches were reported along the highway 75 corridor from Owl Ck south of Galena Lodge to just over Galena Summit on the Stanley side. Just about anyone that went out yesterday reported nearly continuous snowpack collapsing or cracking.  

Nearly all of the avalanches seen yesterday were small. In large part due to poor visibility and the extremely cautious travel routes of those that were out. Today's improving weather should allow a better glimpse into the alpine, where I'd expect to see evidence of a widespread natural avalanche cycle. Safely traveling through the mountains today will take an abundance of caution. I'll be surprised if we don't hear of human-triggered avalanches today and through the weekend.

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